Page 4 of 4 FirstFirst ... 234
Results 31 to 34 of 34

Thread: quadratic mean of all values of r of a circle

  1. #31
    New Member
    Join Date
    Mar 2013
    Posts
    34
    mmm4444bot: Interesting. It could be that there is an error in the exercise and what you gave is what was intended (in your final quadratic mean, you forgot r). However, it is also an odd coincidence that 2π is about 6, which is the solution for 2 times the area.

    Subhotosh Khan: There is no reference to concentricity. In an exercise that says to find a minimum volume, there is no reference to differentiation, but that is the way to the solution.

    Subhotosh Khan and stapel: I tried to attach a drawing I made with Paint as to what I mean about concentric elements. It let me choose what file to upload, but there was no "OK", or "Continue" or "Upload" or anything to complete the attach.
    To describe it, imagine a circle whose radius is R. A concentric element would be inside said circle with radius r and a width of dr. The sum of all dr would be R. Again, this is only a guess as to some relationship that I proposed that might lead to the solution of twice the area, unless mmm4444bot is correct about an error in the exercise..




  2. #32
    Elite Member mmm4444bot's Avatar
    Join Date
    Oct 2005
    Location
    Seattle
    Posts
    8,544
    Quote Originally Posted by ray5450 View Post
    in your final quadratic mean, you forgot r
    I sure did. Fixed now, thanks.


    I tried to attach a drawing I made with Paint as to what I mean about concentric elements. It let me choose what file to upload, but there was no "OK", or "Continue" or "Upload" or anything to complete the attach.
    You begin by using the Manage Attachments button. On the resulting pop-up window, you click the Add Files button. That causes another pop-up window (which defaults to using your computer as the image source, instead of the web), and this window contains both the Choose File and Upload buttons. It's also explained in the FAQ.
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  3. #33
    New Member
    Join Date
    Mar 2013
    Posts
    34
    Okay, I tried again...
    Attached Images Attached Images

  4. #34
    New Member
    Join Date
    Mar 2013
    Posts
    34
    Whether it helps or not, is this diagram clear?

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •